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178 IGUANA  •  VOLUME 13, NUMBER 3  •  SEPTEMBER 2006 ARIANO-SÁNCHEZ

Guatemalan Beaded Lizards (Heloderma horridum charlesbogerti) are endemic to the semiarid Motagua Valley in Guatemala.

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The semiarid Motagua Valley in Guatemala is one of the
most endangered and unique ecosystems in the world. This

region receives the lowest average rainfall in Central America (ca.
500 mm) and is characterized by many endemic species. This
region once occupied about 200,000 ha, most of which is now
a heterogeneous landscape of crops, grasslands, thornscrub, and
very dry deciduous forest remnants. The latter are home to the
very rarely encountered endemic Guatemalan Beaded Lizard
(Heloderma horridum charlesbogerti).

Natural History
The Guatemalan Beaded Lizard, which (in conjunction with H.
h. alvarezi) may actually represent a distinct species, is restricted
to forest remnants in the Motagua Valley. The Beaded Lizards
and Gila Monsters (H. suspectum) comprise the Helodermatidae,
a unique family of lizards with venom glands. Although the sub-
species H. h. charlesbogerti was described in 1988, it had not
been studied until very recently.

This species reduces its activity drastically during the dry
season (December to May), when individuals remain almost
constantly concealed in subterranean shelters that provide pro-
tection from extreme temperatures and desiccation. Suitable
shelters are limited resources in the remaining forests and may
limit population size. Recent estimates, based on average home-
range sizes of this and other subspecies and on remaining avail-
able habitat, suggest that only 200–250 individuals remain in
the wild.

Only 24,000 ha of suitable habitat remain, and these are
comprised of patches ranging in size from < 1 ha to around
1,500 ha. If only those patches of > 100 ha are considered, the
potential distribution of these lizards is reduced to 17,000 ha.
This area comprises the localities of Cabañas, Usumatlán, and
Gualán in the Zacapa Department, and El Jicaro in the El
Progreso Department, in the semiarid region of the Motagua
Valley in Guatemala.

Conservation Status
The Guatemalan Beaded Lizard is almost certainly the most
endangered species in Guatemala. It is listed in CITES

Appendix II and as vulnerable in the IUCN Red List of
Threatened species. The greatest threats to its continued exis-
tence are agricultural practices not compatible with conserva-

The Guatemalan Beaded Lizard:
Endangered Inhabitant of a 

Unique Ecosystem
Daniel Ariano-Sánchez

Director, Research & Conservation Projects
Zootropic Organization

Ciudad Guatemala, Guatemala
dariano@zootropic.com

Photographs by the author except where indicated.

IGUANA  •  VOLUME 13, NUMBER 3  •  SEPTEMBER 2006 179GUATEMALAN BEADED LIZARD

�

A female Guatemalan Beaded Lizard (Heloderma horridum charles-
bogerti) in the wild.

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tion, illegal extraction for local and international collectors, and
persecution by local people, who consider it to be dangerous.
From 1994–2000, an estimated 30 animals were illegally col-
lected, and, from 2000–2001, local people at only one locality
killed 11 lizards.

Another factor that may have had a negative impact on
wild populations of H. h. charlesbogerti was Hurricane Mitch in
November 1998. Vast zones of the most arid portions of the
Motagua Valley were flooded that year, causing considerable
damage to the human population and to the wildlife of the
region. Late October-early November is the beginning of the
egg-laying season for Beaded Lizards, and the eggs are known to
be very sensitive to humidity. A number of clutches may well

have been lost or failed to hatch because of floods.
Unfortunately, no baseline data existed at that time, so the
impact on wild populations cannot be evaluated.

Conservation Efforts
Since the initiation of intensive studies in 2002, conservation
efforts have increased, in part because of an increased public
awareness regarding the threatened status of the species. These
efforts have been led by a local NGO, “Zootropic.” The pro-
gram is constituted of four basic elements: (1) education, (2)
applied scientific research, (3) habitat conservation, and (4)
development of conservation policies for this species. Research
has focused on determining distribution, the nature and cause
of threats, the basic biology of the species, movement patterns,
shelter use and their availability as a limiting resource, and char-
acterization of venom. The education program has been ongo-
ing since mid-2003 in localities where this species occurs and in
coordination with local authorities and local partners of
Zootropic. The habitat conservation component has two
approaches: (1) conservation of private lands by commitment of
owners to preserve forest remnants and (2) an official declara-
tion of municipal, communal, and private natural reserves as

180 IGUANA  •  VOLUME 13, NUMBER 3  •  SEPTEMBER 2006 ARIANO-SÁNCHEZ

Guatemalan Beaded Lizards (Heloderma horridum charlesbogerti)
emerging from and resting in subterranean shelters.

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Land-use changes within the distribution of Heloderma horridum
charlesbogerti: Changes are primarily attributable to production of com-
mercial crops like melon (top) and subsistence crops like corn (bottom).

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IGUANA  •  VOLUME 13, NUMBER 3  •  SEPTEMBER 2006 181GUATEMALAN BEADED LIZARD

part of the Guatemalan protected areas system. Finally,
Zootropic has promoted and coordinated the planning of a
national strategy for Guatemalan Beaded Lizard conservation
with the support of The Nature Conservancy. This conservation
plan was generated in collaboration with local and international
experts representing 16 institutions, including the National
Council of Protected Areas (CONAP), which is Guatemala’s
official institution in charge of biodiversity conservation.

Local People: Poachers and Conservationists
Considering that two of the most serious threats to the species
are illegal trade and extermination, environmental education has
been strongly emphasized. This program actively engages local
people, some of whom were poachers of Heloderma in the past.
Today, they are proud conservationists. Demonstrating the
uniqueness and importance of conserving this species, locals have
learned that many of the myths associated with the species were
not true. Some individuals have learned to use the radioteleme-
try equipment and implement basic research techniques. The
principal objective of this involvement is to incorporate members
of the community in the research in order to instill an apprecia-
tion for this species. Only with a strong relationship between

locals and scientific researchers is an understanding of the impor-
tance of the project possible. These people now function as pro-
moters of the conservation plan within their own communities.

Potential distribution of Heloderma horridum charlesbogerti in the semiarid Motagua Valley in Guatemala (indicated by the shaded area on the
map). Determination of the potential distribution took into account historical and recent collection sites, land use patterns, rainfall and tempera-
ture data, forest types, and distances to human settlements.

Current research is using radiotelemetry to reveal movement patterns
and shelter selection in the wild

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182 IGUANA  •  VOLUME 13, NUMBER 3  •  SEPTEMBER 2006 ARIANO-SÁNCHEZ

Next Steps
In spite of strong conservation efforts already implemented, gaps
still exist in the data. Very little is known, for instance, about the
species’ ecology, characteristics of the nests, and which specific phys-
ical factors affect shelter selection. Reproductive behavior has not
been observed or documented in the wild. Such data are of great
importance for implementing ex situ and in situ conservation strate-
gies. Also, emphasis continues on strengthening environmental edu-
cation programs and continuing to promote the conservation of this
species to official environmental agencies. A captive-breeding pro-
gram has been initiated. Within the year, genetic analyses of wild
and captive populations are slated to begin.

A group of local and international experts (representing 16 institutions)
are collectively responsible for the National Strategy for Guatemalan
Beaded Lizard Conservation.

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The environmental education program addresses local farmers (top)
and school children (bottom).

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A Heloderma horridum charlesbogerti with a radiotransmiter is entering a subterranean shelter.

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IGUANA  •  VOLUME 13, NUMBER 3  •  SEPTEMBER 2006 183GUATEMALAN BEADED LIZARD

Acknowledgements
I thank Daniel Beck, Brad Lock, and John Binns for information and
suggestions that improved this paper. I thank Lester Melendez for the
use of some photographs, and all the institutions and persons that
supported this project at different times: Craig Ivanyi (Arizona-
Sonora Desert Museum), Atlanta Zoo, Idea Wild, German
Academic Exchange Service, The Nature Conservancy, National
Fund for Nature Conservation (FONACON), National Council of
Protected Areas (CONAP), Nature Defenders Foundation (FDN),
University of the Valley of Guatemala (UVG), University of Costa
Rica (UCR), and especially Gilberto Salazar, Luis Alvarado, Antonio
Urbina, Rodrigo Botrán, and Alejandro Gonzalez from from
Zootropic for supporting, participating, and believing in this project.

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Land owners have designated forest remnants on their farms for protection; this large remnant near El Arenal is inhabited by Guatemalan Beaded
Lizards.

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